1. Field of the Invention
The invention deals with the field of lighting and/or of light signaling, notably for a motor vehicle. More particularly, the invention deals with the field of the mounting and the electrical connection of light sources of the light-emitting diode, LED, type. The invention deals with a support for light source(s) and a module comprising such a support.
2. Description of the Related Art
The use of light sources of light-emitting diode type in lighting and/or light signaling systems is increasingly widespread. In the field of motor vehicle lighting and light signaling, so-called power diodes are used. The latter are often generally planar and of the surface mount type. Surface-mounting of components consists in soldering the components of a board to its surface (SMD, standing for “surface mounted device”), rather than having the leads pass therethrough. Since the light-emitting diodes are semiconductors, they are affected by temperature: the more they heat up, the more their direct junction voltage decreases, and their light yield is degraded. For reasons of reliability and light performance, thermal management measures have to be implemented, in particular for the power modules.
The published patent document FR 2 840 151 A1, which is equivalent to U.S. Publication 2004/0029436 and U.S. Pat. No. 6,821,143, discloses a power light-emitting diode support for a lighting or light signaling system for a motor vehicle. The diode is glued onto a metal substrate forming a heat sink. This substrate is fixed to an electrically insulating plate. It comprises two notches each extending, in opposite directions, from a substrate edge to the edge of the diode. A conductive tab is arranged in each of the two notches in order to ensure an electrical link between the diode and the printed circuit on the plate, the metal substrate ensuring the cooling of the diode. Each of the tabs is linked by soldering to one of the electrodes of the diode. The configuration of this teaching is advantageous inasmuch as it makes it possible to ensure a cooling of the diode while supporting the latter by means of a conventional insulating plate. The cooling capacity is however limited, essentially because of the limited size of the metal substrate. Furthermore, the positioning accuracy is also limited given the addition of the positioning tolerances of the diode relative to the dissipating substrate, of the latter relative to the plate and then of the latter relative to the reflector or to the frame of the lighting or light signaling module.
The published patent document FR 2 853 200 A1, which is equivalent to U.S. Publication 2004/0190294 and U.S. Pat. No. 7,210,833, discloses, similarly to the preceding document, a power light-emitting diode support for a lighting or light signaling system for a motor vehicle. Similarly to the preceding document, the diode is fixed to a metal substrate suitable for dissipating the heat produced by the diode. This substrate is fixed to a plate of electrically insulating material and comprises two opposing notches through which extend, respectively, two electrical connection pins or tabs. Alternatively to the procedure of gluing the diode onto the thermal dissipation substrate disclosed in the preceding document, the diode of this teaching comprises a baseplate composed essentially of copper which is fixed to the substrate by spot laser soldering. These measures are intended to avoid the drawbacks inherent in the use of glue, namely the drying or cross-linking time, the means necessary to its application, its application time and the means for holding the diode on the dissipating substrate until the glue ensures that it is fixed. Similarly to the preceding document, the cooling capacity in this construction is limited, essentially because of the limited size of the metal substrate. Again similarly to the preceding document, the accuracy of positioning of the diode is limited.
It has also been proposed to arrange a plate comprising an electrical power supply circuit on a substrate. One or more light-emitting diodes, glued onto the same generally planar substrate and being able to dissipate the heat produced by the diodes, are connected to the power supply circuit by wire-bonding links. In this case, there is the risk of the elements of the circuit or the plate casting shadow on a part of the light sources or at least on the geometrical location of their light beam, thus reducing their usefulness.